Precompiled custom shaders support on WP8

Please consider adding my patch to allow loading of custom precompiled shaders. I have attached it. Basically it allows you to pass your own array instead of depending on COCOS to have the precompiled array already in precompiledshaders.h (obviously this is untenable for user shaders).

Additionally, I have a patch for my mods to the glslprecompiler project in angle. This allows it to create Cocos2d-x compatible binary shaders.

Without these, I believe we cannot do 3rd party shaders, which just sucks if you are already using them!